Got a crash after fission reactor overheated.
crash-2017-08-21_08.22.23-server.txt
Using v2.3a with temp fix from #124

Probably related to #104 ?

I might have made a mistake, or, just like with many other current issues, this is related to the mod being built on an old forge version. Either way, I'm on it :)

I was never actually able to recreate this, but I did update the meltdown code for the latest release, so could you see if your issue goes away?

I also managed to crash All The Mods with Nuclearcraft 2.3 several times, but not all times, by creating a small reactor in a single player game without cooling and just turn it on. It would crash the game and after returning I would see lava pouring out. The controller is always replaced by a lava source block.

But has the issue disappeared in NC 2.5?

Can confirm, it still occurs in 2.5a on my server. We're running forge 14.23.0.2517 in minecraft 1.12.2 using nuclearcraft 2.5a.

Crash report uploaded to https://pastebin.com/QBL4nXvU but it looks like the primary issue is here:

java.lang.IllegalArgumentException: Cannot get property PropertyDirection{name=facing, clazz=class net.minecraft.util.EnumFacing, values=[north, south, west, east]} as it does not exist in BlockStateContainer{block=minecraft:flowing_lava, properties=[level]}

Fixed now thanks to the recent commit by dizzyd :)